Section 89(4)(C) in The Central Goods and Services Tax Rules, 2017
(C)[ "Turnover of zero-rated supply of goods" means the value of zero-rated supply of goods made during the relevant period without payment of tax under bond or letter of undertaking or the value which is 1.5 times the value of like goods domestically supplied by the same or, similarly placed, supplier, as declared by the supplier, whichever is less, other than the turnover of supplies in respect of which refund is claimed under sub-rules (4A) or (4B) or both;]